Mobile Networking Challenges 293
In a more general sense, the topology control problem in MANET
can be characterized by a triple of the form <M, P, O>, where M
denotes the graph model (directional or unidirectional), P denotes
the desired graph property such as the k-edge connected and bounded
maximum node degree, and O represents the power minimiza-
tion objective (i.e., maximum power and total power) [27]. The
problem of minimizing the maximum power is NP-complete (A deci-
sion problem is NP-complete if and only if it is in NP and it is
NP-hard. Readers who are interested in computational complex-
ity can refer to M. Garey and D. Johnson’s book “Computers
and Intractability: A Guide to the Theory of NP-Completeness”.).
Furthermore, the problem of